Compare Two Stroke with four stroke Engine:

Two Stroke Engine

In two stroke engine all the four operation that is suction, compression, ignition and exhaust are completed in one revolution of crank shaft.

Four Stroke Engine

In four stroke engine all the four operations are completed in the two revolutions of crank shaft.

Application of 2-stroke Engines

Two stroke  engine  are  generally  used  where  low  cost,  compactness  and  light  weight  are  the  major considerations

following are the major differences between four stroke and two stroke engines.

1. In four stroke engine, power is developed in every alternate revolution of crankshaft whereas; in a two stroke engine power is developed in each revolution of crankshaft.

2. In two stroke engine, the torque is more uniform than in four stroke engine thus a lighter flywheel is necessary in two stroke engine, whereas four stroke engines requires a heavier flywheel.

3. The suction and exhaust are opened and closed by the mechanical valves in four stroke engine, whereas in two stroke engine, the piston opens and closes the ports itself.

4. In four stroke engine the charge directly enters into cylinder whereas in two stroke engine the charge 1^st enters the crankcase and then flows into cylinder.

5. The crankcase of two stroke engine is closed pressure tight chamber whereas crankcase of four stroke engine even though closed is not pressure tight chamber.

6. In four stroke engine piston drives out the burnt gases during exhaust stroke, while, in two stroke engine high pressure fresh charge scavenges out burnt gases.

7. The lubricating oil consumption in two stroke engine is more than in four stroke engine.

8. A two stroke engine produces more noise than four stroke engine.

9. As the fuel burns in every revolution of crankshaft in two stroke engine the rate of cooling is more than in four stroke engine.

10. A valve less two stroke engines runs in either direction, whereas four stroke engines cannot run in either direction.